Piezoelectric component and method for manufacturing the same

ABSTRACT

The present invention provides a compact piezoelectric component in which degradation in the characteristic thereof is further suppressed, and a method for manufacturing the same. A SAW device  21  includes a SAW element  16  having an IDT  2  and a conductive pad  3  connected to the IDT  2  formed on a piezoelectric substrate  1 ; and an external terminal  12 . The SAW device  21  also includes an insulating layer  7  having an exciting portion protective opening  9  serving as space for protecting a SAW-exciting portion including the IDT  2  and a conductive opening  8 . The external terminal  12  is connected to the conductive pad  3  through a wiring  11  extending in the conductive opening  8

TECHNICAL FIELD

[0001] The present invention relates to piezoelectric components such assurface acoustic wave devices and piezoelectric thin-film filters usedfor delay lines and filters or the like and a method for manufacturingthe same. In particular, the present invention relates to piezoelectriccomponents packaged in a chip size and a method for manufacturing thesame.

BACKGROUND ART

[0002] In recent years, a decrease in size and weight of electronicdevices has caused a growing demand for multifunctional electroniccomponents. In this circumstance, piezoelectric components, such assurface acoustic wave filters (hereinafter referred to as SAW filters)serving as SAW devices and piezoelectric filters including piezoelectricthin-film resonators, used for communication apparatuses such asportable phones are required to be decreased in size and weight.

[0003] A piezoelectric filter includes piezoelectric resonators arrangedin a ladder pattern or lattice pattern. Each resonator includes an Sisubstrate having an opening or a recessed portion; and a vibratingportion formed by sandwiching the upper and lower surfaces of athin-film portion having at least one layer of piezoelectric thin-film(comprising ZnO or AlN) formed on the opening or the recessed portion byat least a pair of upper and lower electrodes facing each other.Alternatively, the Si substrate may not include an opening or recessedportion, and space may be provided between the lower electrode and theSi substrate. In this type of piezoelectric filter, thicknesslongitudinal vibration generated at the vibrating portion is used.Therefore, space for vibration must be ensured and the vibrating portionmust be protected against water and dust.

[0004] On the other hand, a SAW filter is formed by arranginginterdigital transducers (hereinafter abbreviated as IDTs), eachincluding a pair of comb electrodes comprising metal such as Al, on apiezoelectric substrate comprising crystal, LiTaO₃, or LiNbO₃. In such aSAW filter, vibrating space for the IDTs and a SAW-propagating portionon the piezoelectric substrate must be ensured, and the IDTs must beprotected against water and dust.

[0005] In the above-described piezoelectric filter and SAW filter, a diebonding agent is applied to the bottom surface of a package comprising aceramic material such as alumina, elements of the piezoelectric filteror the SAW filter are mounted on the package by die bonding, a terminalin the package is connected to electrodes of the elements by wirebonding, and then the package is sealed by a lid. Alternatively, in theabove-described piezoelectric filter and SAW filter, an electrode landis formed on the bottom surface of the package comprising alumina,elements of the piezoelectric filter or the SAW filter are mounted onthe package by flip-chip bonding, and then the package is sealed by alid for realizing miniaturization.

[0006] In the above-described configuration, however, even though theelements in the piezoelectric filter or the SAW filter are miniaturized,miniaturization and lower profile of the piezoelectric filter and SAWfilter cannot be realized as long as the package is not miniaturized.Also, the cost for compact package is high. Particularly, in thepiezoelectric filter, the vibrating portion is formed on the opening orrecessed portion of the substrate, and thus the vibrating portion may bebroken due to impact caused by dicing of elements, and pick up or diebonding of elements at packaging.

[0007] On the other hand, bumps are used for packaging in PatentDocuments 1 to 3. According to these Patent Documents, flip-chipmounting, in which a SAW element is bonded to a base substrate by usingbumps on the base substrate, is adopted. In this method, space for wirebonding is not necessary, which results in miniaturization of a SAWfilter. However, conductive pads corresponding to the bumps must beformed in the SAW element, which reduces an effective area of the SAWelement. As a result, miniaturization of the SAW filter becomesdifficult and cost for forming the bumps is required.

[0008] In Patent Document 4, a SAW element is mounted on a basesubstrate provided with a through hole facing a lead electrode of theSAW element and a conductive agent is filled in the through hole, so asto form an external circuit connecting portion. In this way, the SAWfilter is miniaturized.

[0009] [Patent Document 1]

[0010] Japanese Unexamined Patent Application Publication No. 2001-94390

[0011] [Patent Document 2]

[0012] Japanese Unexamined Patent Application Publication No. 11-150441

[0013] [Patent Document 3]

[0014] Japanese Unexamined Patent Application Publication No. 2001-60642

[0015] [Patent Document 4]

[0016] Japanese Unexamined Patent Application Publication No.2001-244785

DISCLOSURE OF INVENTION

[0017] In the configuration described in Patent Document 4, however,since the SAW filter is formed by bonding the base substrate to the SAWelement, the thickness of the SAW filter increases due to the basesubstrate.

[0018] The present invention has been made in view of theabove-described problems in the known arts, and it is an object of thepresent invention to provide a compact piezoelectric component and amethod for manufacturing the same.

[0019] In order to solve the above-described problems, a piezoelectriccomponent of the present invention includes a piezoelectric elementincluding at least one vibrating portion and an element wiring connectedto the vibrating portion, which are formed on a substrate; and anexternal terminal. The piezoelectric component also includes aninsulating layer including an opening serving as space for protectingthe vibrating portion and a conductive opening. The external terminal isconnected to the element wiring through an external terminal connectingmember formed in the conductive opening.

[0020] With this configuration, the vibrating portion is protected bythe opening serving as space for protecting the vibrating portion in theinsulating layer. Therefore, degradation in the characteristic of thepiezoelectric component due to packaging can be prevented. Also, thepiezoelectric component does not require an element causing an increasein the thickness of the piezoelectric component, such as a substratebonded for protecting the vibrating portion, and thus miniaturization,lower profile, and lower cost of the piezoelectric component can berealized. Further, since the position of the external terminal connectedto the conductive opening can be arbitrarily changed on the insulatinglayer in accordance with an externally connected circuit. That is, thepositioning freedom of the external terminal can be increased.

[0021] Preferably, a protective film is formed in the opening. With thisconfiguration, the vibrating portion can be protected more reliably.

[0022] Also, the opening is preferably covered by a lid. With thisconfiguration, the vibrating portion can be protected more reliably.

[0023] Further, in order to solve the above-described problems, apiezoelectric component of the present invention includes apiezoelectric element including at least one vibrating portion and anelement wiring connected to the vibrating portion, which are formed on asubstrate; and an external terminal. The piezoelectric component furtherincludes an insulating layer which includes an opening serving as spacefor protecting the vibrating portion and a conductive opening and whichis provided with a wiring connected to the element wiring through theconductive opening; and a second insulating layer which protects thewiring and which includes a second opening positioned over the openingand a second conductive opening, the second insulating layer beingprovided on the insulating layer. The external terminal is connected tothe wiring through an external terminal connecting member formed in thesecond conductive opening.

[0024] With this configuration, since the wiring is protected by thesecond insulating layer, short circuit or the like caused by contactwith the wiring at packaging of a SAW device can be prevented.

[0025] Additionally, in the piezoelectric component of the presentinvention, the wiring preferably includes any of a capacitor orinductor. With this configuration, a capacitor or inductor need not beprovided independently, and thus the piezoelectric component can beminiaturized.

[0026] Preferably, a protective film is formed in the second opening.With this configuration, the vibrating portion can be protected morereliably.

[0027] Also, the second opening is preferably covered by a lid. Withthis configuration, the vibrating portion can be protected morereliably.

[0028] The piezoelectric element may be a SAW element including avibrating portion having an IDT formed on a substrate.

[0029] Alternatively, the piezoelectric element may be a piezoelectricthin-film element including a vibrating portion formed by sandwichingthe upper and lower surfaces of a thin-film portion having at least alayer of piezoelectric thin-film formed on an opening or a recessedportion in a substrate by at least a pair of upper and lower electrodesfacing each other.

[0030] Alternatively, the piezoelectric element may be a piezoelectricthin-film element including a vibrating portion formed by sandwichingthe upper and lower surfaces of a thin-film portion having at least alayer of piezoelectric thin-film formed on a substrate by at least apair of upper and lower electrodes facing each other, space beingprovided between the substrate and the lower electrode in the vibratingportion.

[0031] In order to solve the above-described problems, the presentinvention provides a method for manufacturing a piezoelectric componentincluding a piezoelectric element including at least one vibratingportion and an element wiring connected to the vibrating portion, whichare formed on a substrate; and an external terminal. The method includesa step of manufacturing the piezoelectric element by forming the atleast one vibrating portion and the element wiring connected to thevibrating portion on the substrate; a step of forming an insulatinglayer including an opening serving as space for protecting the vibratingportion and a conductive opening; a step of forming a first wiring so asto be connected to the element wiring through the conductive opening;and a step of forming the external terminal so as to be connected to thefirst wiring.

[0032] The piezoelectric element may be a SAW element including avibrating portion having an IDT formed on a substrate.

[0033] According to the above-described method, the vibrating portioncan be protected by the opening serving as space for protecting thevibrating portion in the insulating layer. Therefore, degradation in thecharacteristic of the piezoelectric component due to packaging can beprevented. Also, the piezoelectric component does not require an elementcausing an increase in the thickness of the piezoelectric component,such as a substrate bonded for protecting the vibrating portion, andthus miniaturization, lower profile, and lower cost of the piezoelectriccomponent can be realized. Further, since the position of the externalterminal connected to the conductive opening can be arbitrarily changedon the insulating layer in accordance with an externally connectedcircuit. That is, the positioning freedom of the external terminal canbe increased.

[0034] Also, in order to solve the above-described problems, the presentinvention provides a method for manufacturing a piezoelectric componentincluding a piezoelectric element including at least one vibratingportion and an element wiring connected to the vibrating portion, whichare formed on a substrate; and an external terminal. The method includesa step of manufacturing the piezoelectric element by forming the atleast one vibrating portion and the element wiring connected to thevibrating portion on the substrate; a step of forming a protective layerfor protecting the vibrating portion in the piezoelectric element; astep of forming an insulating layer including an opening serving asspace for protecting the vibrating portion and a conductive opening; astep of forming a first wiring so as to be connected to the elementwiring through the conductive opening; and a step of forming theexternal terminal so as to be connected to the first wiring.

[0035] The piezoelectric element may be a SAW element including avibrating portion having an IDT formed on a substrate.

[0036] Alternatively, the piezoelectric element may be a piezoelectricthin-film element including a vibrating portion formed by sandwichingthe upper and lower surfaces of a thin-film portion having at least alayer of piezoelectric thin-film formed on an opening or a recessedportion in a substrate by at least a pair of upper and lower electrodesfacing each other.

[0037] Alternatively, the piezoelectric element may be a piezoelectricthin-film element including a vibrating portion formed by sandwichingthe upper and lower surfaces of a thin-film portion having at least alayer of piezoelectric thin-film formed on a substrate by at least apair of upper and lower electrodes facing each other, space beingprovided between the substrate and the lower electrode in the vibratingportion.

[0038] According to the above-described method, the vibrating portioncan be protected by the protective film. Also, the vibrating portion canbe protected by the opening serving as space for protecting thevibrating portion in the insulating layer. Therefore, degradation in thecharacteristic of the piezoelectric filter due to packaging can beprevented. Also, the piezoelectric component does not require an elementcausing an increase in the thickness of the piezoelectric component,such as a substrate facing the vibrating portion for protecting thevibrating portion, and thus miniaturization, lower profile, and lowercost of the piezoelectric component can be realized. Further, since theposition of the external terminal connected to the conductive openingcan be arbitrarily changed on the insulating layer in accordance with anexternally connected circuit. That is, the positioning freedom of theexternal terminal can be increased.

[0039] Further, in order to solve the above-described problems, thepresent invention provides a method for manufacturing a piezoelectriccomponent including a piezoelectric element including at least onevibrating portion and an element wiring connected to the vibratingportion, which are formed on a substrate; and an external terminal. Themethod includes a step of manufacturing the piezoelectric element byforming the at least one vibrating portion and the element wiringconnected to the vibrating portion on the substrate; a step of formingan insulating layer including an opening serving as space for protectingthe vibrating portion and a conductive opening; a step of forming afirst wiring so as to be connected to the element wiring through theconductive opening; a step of forming a second insulating layerincluding a second conductive opening on the insulating layer; a step offorming a second wiring so as to be connected to the first wiringthrough the second conductive opening; and a step of forming theexternal terminal so as to be connected to the first wiring through thesecond wiring.

[0040] Also, in order to solve the above-described problems, the presentinvention provides a method for manufacturing a piezoelectric componentincluding a piezoelectric element including at least one vibratingportion and an element wiring connected to the vibrating portion, whichare formed on a substrate; and an external terminal. The method includesa step of manufacturing the piezoelectric element by forming the atleast one vibrating portion and the element wiring connected to thevibrating portion on the substrate; a step of forming a protective layerfor protecting the vibrating portion in the piezoelectric element; astep of forming an insulating layer including an opening serving asspace for protecting the vibrating portion and a conductive opening; astep of forming a first wiring so as to be connected to the elementwiring through the conductive opening; a step of forming a secondinsulating layer including a second conductive opening on the insulatinglayer; a step of forming a second wiring so as to be connected to thefirst wiring through the second conductive opening; and a step offorming the external terminal so as to be connected to the first wiringthrough the second wiring.

[0041] According to the above-described method, the first wiring isprotected by the second insulating layer, and thus short circuit or thelike caused by contact with the first wiring at packaging of thepiezoelectric component can be prevented.

[0042] Preferably, the method further includes a step of polishing thepiezoelectric substrate.

[0043] According to the above-described method, the piezoelectricsubstrate can be thinned by polishing it. Preferably, the polishing stepis performed after the insulating layer or the like is formed so as toreinforce the piezoelectric substrate. By this polishing step, theprofile of the SAW device can be further reduced.

[0044] In the piezoelectric component of the present invention, thevibrating portion in the piezoelectric element is protected by aprotective layer or a protective space forming member. Accordingly,degradation in the characteristic of the piezoelectric component due topackaging can be prevented. Also, the piezoelectric component does notrequire an element causing an increase in the thickness of thepiezoelectric component, such as a substrate facing the vibratingportion for protecting the vibrating portion, and thus miniaturization,lower profile, and lower cost of the piezoelectric component can berealized.

BRIEF DESCRIPTION OF THE DRAWINGS

[0045]FIG. 1 includes cross-sectional views showing a process ofmanufacturing a SAW device according to a first embodiment of thepresent invention.

[0046]FIG. 2 includes cross-sectional views showing a process ofmanufacturing a SAW device according to a second embodiment of thepresent invention.

[0047]FIG. 3 includes cross-sectional views showing the process ofmanufacturing the SAW device according to the second embodiment of thepresent invention.

[0048]FIG. 4 is a circuit diagram showing a SAW device according to amodification of the first embodiment of the present invention.

[0049]FIG. 5 is a plan view showing a SAW element of the SAW deviceaccording to the modification of the first embodiment of the presentinvention.

[0050]FIG. 6 is a plan view showing a state where an insulating layer isformed on the SAW element shown in FIG. 5.

[0051]FIG. 7 is a plan view showing a state where external terminals areformed on the insulating layer shown in FIG. 6.

[0052]FIG. 8 is a cross-sectional view showing the SAW device accordingto the modification of the first embodiment of the present invention.

[0053]FIG. 9 is a circuit diagram showing a SAW device according toanother modification of the first embodiment of the present invention.

[0054]FIG. 10 is a plan view showing a SAW element of the SAW deviceaccording to the above-described another modification of the firstembodiment of the present invention.

[0055]FIG. 11 is a plan view showing a state where an insulating layeris formed on the SAW element shown in FIG. 10.

[0056]FIG. 12 is a plan view showing a state where external terminalsare formed on the insulating layer shown in FIG. 11.

[0057]FIG. 13 is a circuit diagram showing a SAW device according to amodification of the second embodiment of the present invention.

[0058]FIG. 14 is a plan view showing a SAW element of the SAW deviceaccording to the modification of the second embodiment of the presentinvention.

[0059]FIG. 15 is a plan view showing a state where an insulating layeris formed on the SAW element shown in FIG. 14.

[0060]FIG. 16 is a plan view showing a state where wirings are formed onthe insulating layer shown in FIG. 15.

[0061]FIG. 17 is a plan view showing a state where a second insulatinglayer is formed on the insulating layer shown in FIG. 16 and externalterminals are formed.

[0062]FIG. 18 is a cross-sectional view showing the SAW device accordingto the modification of the second embodiment of the present invention.

[0063]FIG. 19 is a circuit diagram showing a SAW device according toanother modification of the second embodiment of the present invention.

[0064]FIG. 20 is a plan view showing a SAW element of the SAW deviceaccording to the above-described another modification of the secondembodiment of the present invention.

[0065]FIG. 21 is a plan view showing a state where an insulating layeris formed on the SAW element shown in FIG. 20.

[0066]FIG. 22 is a plan view showing a state where wirings are formed onthe insulating layer shown in FIG. 21.

[0067]FIG. 23 is a plan view showing a state where a second insulatinglayer is formed on the insulating layer shown in FIG. 22 and externalterminals are formed.

[0068]FIG. 24 is a circuit diagram showing the SAW device according tothe above-described another modification of the second embodiment of thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION FIRST EMBODIMENT

[0069] Hereinafter, an embodiment of the present invention will bedescribed with reference to FIGS. 1 and 4 to 12.

[0070] As shown in FIG. 1, a SAW filter according to this embodimentincludes a SAW element (piezoelectric element) 16 including at least oneIDT (vibrating portion) 2 and a conductive pad (element wiring) 3connected to the IDT 2, which are disposed on a piezoelectric substrate1 comprising LiTaO₃; and an external terminal 12 connected to theconductive pad 3. The external terminal 12 is connected to theconductive pad 3 through a wiring (external terminal connecting member,first wiring) 11 extending in a conductive opening 8 in an insulatinglayer 7, which is laminated on the conductive pad 3 and which comprisesresin. The conductive opening 8 corresponds to a part where theinsulating layer is not disposed on the conductive pad 3. Also, anexciting portion protective opening 9, which serves as space forprotecting a SAW-exciting portion including the IDT 2, is formed in theinsulating layer 7. The exciting portion protective opening 9corresponds to a part where the insulating layer is not provided for theSAW-exciting portion including the IDT 2 on the LiTaO₃ piezoelectricsubstrate 1, that is, a part where a protective film (protective layer)5 is formed.

[0071] In the above-described configuration, the SAW-exciting portionincluding the IDT 2 is protected by the protective film 5. Further, theIDT 2 is protected by the exciting portion protective opening 9 in theinsulating layer 7. With this configuration, degradation in thecharacteristic of the SAW filter due to packaging can be prevented.Also, the above-described SAW filter does not require an element causingan increase in the thickness of the SAW filter, such as a substratebonded for protecting the SAW-exciting portion including the IDT 2, andthus miniaturization, lower profile, and lower cost of the SAW filtercan be realized. That is, packaging can be achieved in the size of theSAW element 16 or a chip.

[0072] Further, since the wiring 11 extending in the conductive opening8 can be arbitrarily formed, the position of the external terminal 12connected to the wiring 11 can be arbitrarily changed in accordance withan externally connected circuit. That is, the positioning freedom of theexternal terminal 12 can be increased.

[0073] The IDT 2 and the conductive pad 3 comprise Al, for example, anda layer comprising Ti, Ni, or Au may be laminated as necessary.Preferably, corrosion can be suppressed by using Au for the top layer.

[0074] As material for the protective film 5, SiN or SiO₂ may be used.

[0075] Even if the protective film 5 is not provided, reliability can beensured to some extent.

[0076] The insulating layer 7 comprises an ordinary photoresistcomprising photosensitive polyimide or a novolac resin, or an insulatingmaterial such as photosensitive benzocyclobuten. Alternatively,benzocyclobuten, a cyclic olefin resin, or an epoxy resin can bepreferably used.

[0077] A protective metallic film 6 may be disposed on the surfaceopposite to the surface provided with the IDT 2 of the LiTaO₃piezoelectric substrate 1. Accordingly, effects of externally comingelectromagnetic waves on the SAW filter can be prevented by thisprotective metallic film 6. The protective metallic film 6 may comprisea material for blocking electromagnetic waves, such as Ti, Al, or NiCr.

[0078] Also, a buffer layer 10 may be disposed on the protectivemetallic film 6. When the protective metallic film is not provided, thebuffer layer 10 may be directly provided on the LiTaO₃ piezoelectricsubstrate 1. The buffer layer 10 alleviates impact caused at packagingof the SAW filter. The buffer layer 10 may comprise a conductive ornon-conductive resin. However, a conductive resin is preferably used,for example, an epoxy resin containing Ag particles. In this way, byapplying conductivity, effects of externally applied electromagneticwaves can be prevented. In addition, pyroelectric destruction of the IDTon the pyroelectric LiTaO₃ substrate can be prevented.

[0079] In the SAW filter, a reinforcing substrate such as an aluminasubstrate may be disposed on the surface opposite to the surfaceprovided with the IDT 2 of the LiTaO₃ piezoelectric substrate 1. Thisreinforcing substrate may be bonded to the surface opposite to thesurface provided with the IDT 2 of the LiTaO₃ piezoelectric substrate 1by using an adhesive or the like. The reinforcing substrate contributesto enhance the strength of the SAW filter.

[0080] Next, a method for manufacturing the SAW filter will be describedwith reference to FIG. 1.

[0081] First, in step 1, the IDT 2, the conductive pad 3, a reflector(not shown), a wiring (element wiring) (not shown), and so on are formedon the 100 mmφ LiTaO₃ substrate (piezoelectric substrate) 1 having athickness of 0.35 mm. That is, the IDT 2, the conductive pad 3, thereflector, the wiring, and so on are formed on the LiTaO₃ piezoelectricsubstrate 1 by a lift-off method such as evaporation by using Al or thelike. Further, an alignment mark 4 for positioning may be formed.Although the shape and size of the alignment mark 4 are not specified,it is circular-shaped and has a size of 10 μmφ in this case. Further,the protective film 5 comprising SiN or SiO₂ is formed at the partprovided with the IDT 2 and the reflector, that is, at the SAW-excitingportion including the IDT 2, by spattering or the like in a thickness of5 nm. The protective metallic film 6 comprising Ti or the like is formedon the surface opposite to the surface provided with the IDT 2 of theLiTaO₃ piezoelectric substrate 1. The protective metallic film 6 may bearbitrarily formed as necessary.

[0082] Then, in step 2, the insulating layer 7 having the conductiveopening 8 and the exciting portion protective opening 9 is formed on thesurface provided with the IDT 2 of the LiTaO₃ piezoelectric substrate 1.The insulating layer 7 can be formed by, for example, applyingphotosensitive polyimide in a thickness of 15 μm, and then performingexposure and development in accordance with a predetermined pattern soas to form the conductive opening 8 and the exciting portion protectiveopening 9.

[0083] Then, in step 3, the wiring 11 and the external terminal 12 areformed. The wiring 11 and the external terminal 12 can be formed by, forexample, forming a resist pattern to be lifted off, forming a metallicfilm by laminating Au (200 nm), Pd (100 nm), and Ti (100 nm) in thisorder by evaporation, and then lifting off the resist. Alternatively,the wiring 11 and the external terminal 12 may be formed by filling aconductive paste in the conductive opening 8 or printing it with asufficient thickness, and then firing the conductive paste. As theconductive paste, a resin Ag paste, a solder paste, an Sn paste whichcan be sintered at a low temperature, or a Zn paste may be used. Also,the wiring 11 and the external terminal 12 may be formed by forming ametallic film and etching the film. In the above-described formingmethods, the wiring 11 and the external terminal 12 can be formed at thesame time, and thus a manufacturing process can be simplified.Alternatively, the wiring 11 and the external terminal 12 may be formedby filling a conductive paste in the conductive opening 8 and sinteringit, and then performing evaporation or printing of the conductive pasteso as to be connected to the sintered conductive paste.

[0084] Then, in step 4, the buffer layer 10 is formed on the protectivemetallic film 6 so as to alleviate impact of packaging. The buffer layer10 may not be formed. When the buffer layer 10 is formed by using aconductive resin, the protective metallic film 6 is not necessary.Further, in this step, the strength of the SAW filter may be enhanced bybonding a reinforcing substrate. Finally, the produced substrate isdiced at predetermined positions so that a SAW filter 21 can beobtained. Although only one SAW element 16 is shown in FIG. 1, aplurality of SAW elements may be formed.

[0085] According to the above-described method, the SAW-exciting portionincluding the IDT 2 can be protected by the protective film 5. Further,the IDT 2 can be protected by space defined by the exciting portionprotective opening 9 in the insulating layer 7. Therefore, degradationin the characteristic of the SAW filter due to packaging can beprevented. Also, in the above-described SAW filter, an element whichcauses an increase in the thickness of the SAW filter, such as asubstrate facing the IDT 2 for protecting the SAW-exciting portionincluding the IDT 2, is not required. Accordingly, miniaturization,lower profile, and lower cost of the SAW filter can be realized.Further, steps of bonding substrates facing each other and etching ofthe substrates can be reduced, and thus the SAW filter can be easilymanufactured while saving time.

[0086] Preferably, the conductive opening 8 is substantially tapered bysetting appropriate exposure conditions. Accordingly, the wiring 11 atthe conductive opening 8 can be formed more easily and also the SAWfilter can be formed more easily.

[0087] If the protective metallic film 6 is not formed, the LiTaO₃piezoelectric substrate 1 may be polished so as to reduce its thicknessin step 2 or thereafter. This polishing step can be performed becausethe LiTaO₃ piezoelectric substrate 1 is reinforced by forming theinsulating layer 7 and so on. In this way, a lower-profile SAW filtercan be obtained.

[0088] Preferably, a negative resist is used for each resist pattern. Byusing a negative resist, remaining of resist at the opening can beprevented.

[0089] In the insulating layer 7, a dicing opening may be formed at adicing portion of the SAW filter. By using this dicing opening,positioning for dicing can be easily performed, and clogging at dicingcan be prevented. Preferably, the width of the dicing opening is equalto the width of a dicing blade used for dicing. Accordingly, a protrudedportion of a product after dicing can be prevented from being damaged.

[0090] Next, a SAW filter according to a modification of this embodimentwill be described with reference to FIGS. 4 to 8.

[0091]FIG. 4 is a circuit diagram showing a SAW filter 100 of thismodification. The SAW filter 100 includes SAW resonators 101 to 105arranged in a ladder pattern, each resonator having an IDT (vibratingportion). The SAW resonators 101 to 103 are series resonators and theSAW resonators 104 and 105 are parallel resonators.

[0092] Hereinafter, the SAW filter 100 will be described with referenceto FIGS. 5 to 8.

[0093] As shown in FIG. 5, the SAW resonators 101 to 105, conductivepads (element wirings) 106 to 109, and wirings (element wirings) 110 to115 are formed on the piezoelectric substrate 1 so as to form a SAWelement 116. Also, a protective film (not shown) for protecting the SAWresonators 101 to 105 is formed.

[0094] Then, as shown in FIG. 6, an insulating layer 124 is formed onthe SAW element 116. The insulating layer 124 includes exciting portionprotective openings 117 to 119 for exposing the SAW resonators 101 to105 and conductive openings 120 to 123 for exposing the conductive pads106 to 109. Alternatively, the insulating layer 124 may cover the entiresurface of the piezoelectric substrate 1.

[0095] Then, as shown in FIG. 7, external terminal connecting members(first wirings) 125 to 128 connected to the conductive pads 106 to 109through the conductive openings 120 to 123 and externals terminals 129to 132 connected to the external terminal connecting members 125 to 128are formed on the insulating layer 124, so as to obtain the SAW filter100.

[0096]FIG. 8 is a cross-sectional view of the produced SAW filter 100,taken along the line A-A′ in FIGS. 5 to 7.

[0097] As shown in FIG. 8, in the SAW filter 100, the exciting portionsincluding the IDTs of the SAW resonators are protected by the excitingportion protective openings 117 and 119. Also, the IDTs of the SAWresonators are protected by protective films 133 and 134. Further, theexciting portion protective openings 117 and 119 may be covered by a lidso as to prevent conductive particles from contacting the IDTs.Accordingly, degradation in the characteristic of the SAW filter can beprevented.

[0098] Next, a SAW filter according to another modification of thisembodiment will be described with reference to FIGS. 9 to 12.

[0099]FIG. 9 is a circuit diagram showing a SAW filter 200 ofthis,modification. The SAW filter 200 includes SAW resonators 201 to 205arranged in a ladder pattern, each resonator having an IDT (vibratingportion). The SAW resonators 201 to 203 are series resonators and theSAW resonators 204 and 205 are parallel resonators.

[0100] Hereinafter, a method for manufacturing the SAW filter 200 willbe described with reference to FIGS. 10 to 12.

[0101] First, as shown in FIG. 10, the SAW resonators 201 to 205 andwirings (element wirings) 206 to 211 are formed on the piezoelectricsubstrate 1 so as to form a SAW element 212.

[0102] Then, as shown in FIG. 11, an insulating layer 220 is formed onthe SAW element 212. The insulating layer 220 includes exciting portionprotective openings 213 to 215 for exposing the SAW resonators 201 to205 and conductive openings 216 to 219 for exposing end portions of thewirings 206 to 211.

[0103] Then, as shown in FIG. 12, external terminal connecting members(first wirings) 221 to 224 connected to the wirings 206, 209, 210, and211 through the conductive openings 216 to 219 and external terminals225 to 228 connected to the external terminal connecting members 221 to224 are formed on the insulating layer 220. Further, protective filmsare formed on the exciting portion protective openings 213 to 215 so asto obtain the SAW filter 200.

[0104] In each of the above-described SAW filters, an element wiring isconnected to each IDT on the piezoelectric substrate, but part of theelement wirings can be omitted. In that case, the conductive openingsare formed in the insulating layer such that a busbar of each IDT isexposed. Accordingly, space for wirings and conductive pads on thepiezoelectric substrate can be saved, and thus the SAW filter can beminiaturized.

SECOND EMBODIMENT

[0105] Hereinafter, another embodiment of the present invention will bedescribed with reference to FIGS. 2 and 3 and 13 to 24. For conveniencein describing, members having the same function as that in the firstembodiment are denoted by the same reference numerals, and thecorresponding description will be omitted.

[0106] As shown in FIGS. 2 and 3, a SAW filter according to thisembodiment is different from that of the first embodiment in that awiring protective layer (second insulating layer) 13 for protecting thewiring 11 to be connected to the external terminal 12 is provided. Theexternal terminal 12 is connected to the wiring 11 through a conductiveopening (second conductive opening) 14 in the wiring protective layer 13.

[0107] Hereinafter, a method for manufacturing the SAW filter will bedescribed with reference to FIGS. 2 and 3.

[0108] In this embodiment, steps 1 and 2 are the same as in the firstembodiment.

[0109] In step 3, only the wiring 11 is formed in this embodiment,whereas the wiring 11 and the external terminal 12 are formed in thefirst embodiment.

[0110] In step 4, the wiring protective layer 13 including theconductive opening 14 and a second opening is formed. In the wiringprotective layer 13, the part of the exciting portion protective opening9 serves as the second opening (second exciting portion protectiveopening). The wiring protective layer 13 can be formed in the same wayas that for the insulating layer 7. For example, the wiring protectivelayer 13 can be formed by applying photosensitive polyimide and thenperforming exposure and development in accordance with a predeterminedpattern so as to include the conductive opening 14 and the secondopening at the exciting portion protective opening 9.

[0111] Then, in step 5, the external terminal 12 is formed in theconductive opening 14. The external terminal 12 may be formed in thesame way as in the first embodiment.

[0112] Then, in step 6, the buffer layer 10 and so on are formed as instep 4 of the first embodiment, and the produced substrate is diced atpredetermined positions, so that a SAW filter 22 can be obtained.

[0113] As described above, the wiring protective layer 13 is formed onthe wiring 11 in this method. Accordingly, short circuit or the likecaused by contact of the external terminal 12 and the wiring 11 atpackaging of the SAW filter can be prevented.

[0114] In this embodiment, the part provided with the exciting portionprotective opening 9 in the wiring protective layer 13 serves as thesecond opening. However, the second opening may not be provided. Whenthe second opening is not provided, the space defined by the excitingportion protective opening 9 in the insulating layer 7 is hollow, sothat the space is provided over the SAW-exciting portion including theIDT 2. Accordingly, degradation in the characteristic of the SAW filterdue to packaging can be prevented. Also, the exciting portion protectiveopening 9 may be covered by a lid.

[0115] The part of the external terminal 12 formed in the conductiveopening 14 can be regarded as an external terminal connecting member(second wiring). That is, the external terminal 12 includes an externalterminal connecting member and an external terminal. Alternatively, theexternal terminal connecting member and the external terminal may beseparated and each of them may be formed in a different method.

[0116] Next, a SAW filter according to a modification of this embodimentwill be described with reference to FIGS. 13 to 18.

[0117]FIG. 13 is a circuit diagram showing a SAW filter 300 of thismodification. The SAW filter 300 includes SAW resonators 301 to 305arranged in a ladder pattern, each resonator including an IDT (vibratingportion). The SAW resonators 301 to 303 are series resonators and theSAW resonators 304 and 305 are parallel resonators. Inductors 306 and307 are connected to the SAW resonators 304 and 305 in series,respectively.

[0118] Hereinafter, the SAW filter 300 will be described with referenceto FIGS. 14 to 17.

[0119] First, as shown in FIG. 14, the SAW resonators 301 to 305,conductive pads (element wirings) 308 to 311, and wirings (elementwirings) 312 to 317 are formed on the piezoelectric substrate 1 so as toform a SAW element 318.

[0120] Then, as shown in FIG. 15, an insulating layer 322 is formed onthe SAW element 318. The insulating layer 322 includes exciting portionprotective openings 318 to 320 for exposing the SAW resonators 301 to305 and conductive openings 318 to 321 for exposing the conductive pads308 to 311. The insulating layer 322 may cover the entire surface of thepiezoelectric substrate 1.

[0121] Then, as shown in FIG. 16, wirings (first wirings) 323 to 326connected to the conductive pads 308 to 311 through the conductiveopenings 318 to 321 are formed on the insulating layer 322. In thisconfiguration, each of the wirings 325 and 326 has an inductor L.Alternatively, each wiring may have a capacitor C. The inductors L inthe wirings 325 and 326 correspond to the inductors 306 and 307.

[0122] Further, as shown in FIG. 17, a second insulating layer 334 isformed on the insulating layer 322. The second insulating layer 334includes second exciting portion protective openings 327 to 329 forexposing the SAW resonators 301 to 305 through the exciting portionprotective openings 318 to 320 and second conductive openings 330 to 333for exposing end portions of the wirings 323 to 326. Then, externalterminals 335 to 338 connected to the wirings 323 to 326 through thesecond conductive openings 330 to 333 are formed on the secondinsulating layer 334, so that the SAW filter 300 can be obtained. Theparts of the external terminals 335 to 338 formed in the secondconductive openings 330 to 333 may be regarded as external terminalconnecting members (second wirings). That is, each of the externalterminals 335 to 338 includes an external terminal connecting member andan external terminal. The external terminal connecting member and theexternal terminal may be separated and each of them may be formed in adifferent method.

[0123]FIG. 18 is a cross-sectional view of the produced SAW filter 300,taken along the line A-A′ in FIGS. 15 to 17.

[0124] As shown in FIG. 18, in the SAW filter 300, vibrating space forthe SAW resonators 304 and 305 can be obtained by providing the excitingportion protective openings 318 and 320 and the second exciting portionprotective openings 327 and 329.

[0125] Alternatively, a protective film may be formed on the IDT of eachSAW resonator so as to protect the IDT. Further, the IDT can beprotected by covering each second exciting portion protective opening bya lid.

[0126] Also, instead of forming the conductive pads 308 to 311, thewirings 312, 315, 316, and 317 may be connected to the wirings 323 to326, respectively.

[0127] Hereinafter, a SAW filter according to another modification ofthis embodiment will be described with reference to FIGS. 19 to 24.

[0128]FIG. 19 is a circuit diagram showing a SAW filter 400 of thismodification. The SAW filter 400 includes SAW resonators 401 to 405arranged in a ladder pattern, each resonator including an IDT (vibratingportion). The SAW resonators 401 to 403 are series resonators and theSAW resonators 404 and 405 are parallel resonators. Inductors 406 and407 are connected to the SAW resonators 404 and 405 in series,respectively.

[0129] Hereinafter, the SAW filter 400 will be described with referenceto FIGS. 20 to 24.

[0130] First, as shown in FIG. 20, the SAW resonators 401 to 405 andwirings (element wirings) 408 to 415 are formed on the piezoelectricsubstrate 1 so as to form a SAW element 416.

[0131] Then, as shown in FIG. 21, an insulating layer 428 is formed onthe SAW element 416. The insulating layer 428 includes exciting portionprotective openings 417 to 419 for exposing the SAW resonators 401 to405 and conductive openings 420 to 427 for exposing the wirings 408 to415. The insulating layer 428 may cover the entire surface of thepiezoelectric substrate 1.

[0132] Then, as shown in FIG. 22, wirings (first wirings) 429 to 432connected to the wirings 408, 411, 412, and 415 through the conductiveopenings 420, 423, 424, and 427 are formed on the insulating layer 428.Also, a connecting wiring (first wiring) 433 for connecting the wirings409 and 413 and a connecting wiring (first wiring) 434 for connectingthe wirings 410 and 414 are formed. In this configuration, each of thewirings 431 and 432 has an inductor L, but each wiring may have acapacitor C. The inductors L in the wirings 431 and 432 correspond tothe inductors 406 and 407.

[0133] Further, as shown in FIG. 23, a second insulating layer 442 isformed on the insulating layer 428. The second insulating layer 442includes second exciting portion protective openings 435 to 437 forexposing the SAW resonators 401 to 405 through the exciting portionprotective openings 417 to 419 and second conductive openings 438 to 441for exposing end portions of the wirings 429 to 432. Then, externalterminals 443 to 446 connected to the wirings 429 to 432 through thesecond conductive openings 438 to 441 are formed on the secondinsulating layer 442. The parts of the external terminals 443 to 446formed in the second conductive openings 438 to 441 may be regarded asexternal terminal connecting members (second wirings). That is, each ofthe external terminals 443 to 446 includes an external terminalconnecting member and an external terminal. The external terminalconnecting member and the external terminal may be separated and each ofthem may be formed in a different way.

[0134] Then, a lid for covering the second exciting portion protectiveopenings 435 to 437 is formed by thermo-compression bonding or the like.Accordingly, the SAW filter 400 can be obtained. Preferably, a platy lidcomprising photosensitive polyimide, polyethylenenaphtalate, liquidcrystal polymer, glass, silicon, or alumina may be used. By using thelid, the IDTs of the SAW resonators can be protected. Further, shortcircuit caused by contact between conductive particles and the IDTs canbe prevented. That is, degradation in the characteristic of the SAWfilter can be prevented.

[0135]FIG. 24 is a cross-sectional view showing the produced SAW filter400, taken along the line A-A′ in FIGS. 20 to 23.

[0136] As shown in FIG. 24, in the SAW filter 400, exciting space(vibrating space) for the IDTs can be obtained by the lid 447, so thatthe IDTs can be protected.

[0137] In the above-described SAW filters, an element wiring isconnected to each IDT on the piezoelectric substrate 1, but the elementwiring may be omitted. In that case, each conductive opening is formedin the insulating layer so that the busbar of each IDT is exposedtherefrom. Accordingly, space for forming wirings and conductive pads onthe piezoelectric substrate can be saved, and thus the SAW filter can beminiaturized.

[0138] In the second embodiment, a SAW filter is used as a piezoelectricfilter. Alternatively, a piezoelectric thin-film filter may be used as apiezoelectric filter. In the piezoelectric thin-film filter, apiezoelectric thin-film element is used as a piezoelectric element. Thepiezoelectric thin-film element includes an Si substrate having anopening or a recessed portion; and at least one piezoelectric thin-filmresonator (vibrating portion) formed by sandwiching the upper and lowersurfaces of a thin-film portion having at least one layer ofpiezoelectric thin-film (comprising ZnO or AlN) formed on the opening orthe recessed portion by at least one pair of upper and lower electrodesfacing each other. Alternatively, the Si substrate may not include anopening or recessed portion, and space may be provided between the lowerelectrode and the Si substrate. In this piezoelectric thin-film filter,vibrating space for the piezoelectric thin-film resonator can be ensuredby an exciting portion protective opening. Also, by sealing the excitingportion protective opening by a lid, the piezoelectric thin-filmresonator can be protected. A protective film is not provided in thepiezoelectric filter.

[0139] In the second embodiment, the second conductive opening isdisplaced from the position of the conductive opening. However, thepositions of the conductive opening and the second conductive openingmay correspond to each other. With this arrangement, conductive pads andpart of the wirings become unnecessary, and thus the piezoelectriccomponent can be miniaturized. Further, by removing the conductive padsand part of the wirings, parasitic capacitance can be reduced.

[0140] In the above-described embodiments, a piezoelectric substrate isused for a SAW element. When wirings are provided on the piezoelectricsubstrate, parasitic capacitance is generated at a part where wiringshaving different potentials face each other in a plane view due to highpermittivity of the piezoelectric substrate, and thus insertion lossoccurs. However, in the SAW filter of the present invention, the numberof wirings provided on the piezoelectric substrate can be reduced, andnecessary wirings can be formed on a resin layer or bonded substratecomprising a material having lower permittivity than that of thepiezoelectric substrate. Accordingly, generation of parasiticcapacitance can be suppressed at a part where wirings having differentpotentials face each other in a plane view.

[0141] The present invention is not limited to the above-describedembodiments, and various modifications can be realized within the scopeof the attached claims. Also, technical methods disclosed in theembodiments may be arbitrarily combined so as to obtain anotherembodiment, which is included in the scope of the present invention.

[0142] According to the present invention, piezoelectric components,such as SAW devices and piezoelectric thin-film filters, used for delaylines and filters can be miniaturized. Further, the piezoelectriccomponents can be used for communication apparatuses such as portablephones, and the communication apparatuses can also be miniaturized.

1. A piezoelectric component comprising a piezoelectric elementincluding at least one vibrating portion and an element wiring connectedto the vibrating portion, which are formed on a substrate; and anexternal terminal, the piezoelectric component comprising: an insulatinglayer including an opening serving as space for protecting the vibratingportion and a conductive opening, wherein the external terminal isconnected to the element wiring through an external terminal connectingmember formed in the conductive opening.
 2. A piezoelectric componentaccording to claim 1, wherein a protective film is formed in theopening.
 3. A piezoelectric component according to claim 1, wherein theopening is covered by a lid.
 4. A piezoelectric component comprising apiezoelectric element including at least one vibrating portion and anelement wiring connected to the vibrating portion, which are formed on asubstrate; and an external terminal, the piezoelectric componentcomprising: an insulating layer which includes an opening serving asspace for protecting the vibrating portion and a conductive opening andwhich is provided with a wiring connected to the element wiring throughthe conductive opening; and a second insulating layer which protects thewiring and which includes a second opening positioned over the openingand a second conductive opening, the second insulating layer beingprovided on the insulating layer, wherein the external terminal isconnected to the wiring through an external terminal connecting memberformed in the second conductive opening.
 5. A piezoelectric componentaccording to claim 4, wherein the wiring comprises any of a capacitor orinductor.
 6. A piezoelectric component according to claim 4, wherein aprotective film is formed in the second opening.
 7. A piezoelectriccomponent according to claim 4, wherein the second opening is covered bya lid.
 8. A piezoelectric component according to claim 1, wherein thepiezoelectric element is a SAW element comprising a vibrating portionincluding an IDT formed on a substrate.
 9. A piezoelectric componentaccording to claim 1, wherein the piezoelectric element is apiezoelectric thin-film element comprising a vibrating portion formed bysandwiching the upper and lower surfaces of a thin-film portion havingat least a layer of piezoelectric thin-film formed on an opening or arecessed portion in a substrate by at least a pair of upper and lowerelectrodes facing each other.
 10. A piezoelectric component according toclaim 1, wherein the piezoelectric element is a piezoelectric thin-filmelement comprising a vibrating portion formed by sandwiching the upperand lower surfaces of a thin-film portion having at least a layer ofpiezoelectric thin-film formed on a substrate by at least a pair ofupper and lower electrodes facing each other, space being providedbetween the substrate and the lower electrode in the vibrating portion.11. A method for manufacturing a piezoelectric component comprising apiezoelectric element including at least one vibrating portion and anelement wiring connected to the vibrating portion, which are formed on asubstrate; and an external terminal, the method comprising: a step ofmanufacturing the piezoelectric element by forming said at least onevibrating portion and the element wiring connected to the vibratingportion on the substrate; a step of forming an insulating layerincluding an opening serving as space for protecting the vibratingportion and a conductive opening; a step of forming a first wiring so asto be connected to the element wiring through the conductive opening;and a step of forming the external terminal so as to be connected to thefirst wiring.
 12. A method for manufacturing a piezoelectric componentcomprising a piezoelectric element including at least one vibratingportion and an element wiring connected to the vibrating portion, whichare formed on a substrate; and an external terminal, the methodcomprising: a step of manufacturing the piezoelectric element by formingsaid at least one vibrating portion and the element wiring connected tothe vibrating portion on the substrate; a step of forming a protectivelayer for protecting the vibrating portion in the piezoelectric element;a step of forming an insulating layer including an opening serving asspace for protecting the vibrating portion and a conductive opening; astep of forming a first wiring so as to be connected to the elementwiring through the conductive opening; and a step of forming theexternal terminal so as to be connected to the first wiring.
 13. Amethod for manufacturing a piezoelectric component according to claim11, wherein the piezoelectric element is a SAW element comprising avibrating portion including an IDT formed on a substrate.
 14. A methodfor manufacturing a piezoelectric component according to claim 12,wherein the piezoelectric element is a piezoelectric thin-film elementcomprising a vibrating portion formed by sandwiching the upper and lowersurfaces of a thin-film portion having at least a layer of piezoelectricthin-film formed on an opening or a recessed portion in a substrate byat least a pair of upper and lower electrodes facing each other.
 15. Amethod for manufacturing a piezoelectric component according to claim12, wherein the piezoelectric element is a piezoelectric thin-filmelement comprising a vibrating portion formed by sandwiching the upperand lower surfaces of a thin-film portion having at least a layer ofpiezoelectric thin-film formed on an opening or a recessed portion in asubstrate by at least a pair of upper and lower electrodes facing eachother.
 16. A method for manufacturing a piezoelectric componentcomprising a piezoelectric element including at least one vibratingportion and an element wiring connected to the vibrating portion, whichare formed on a substrate; and an external terminal, the methodcomprising: a step of manufacturing the piezoelectric element by formingsaid at least one vibrating portion and the element wiring connected tothe vibrating portion on the substrate; a step of forming an insulatinglayer including an opening serving as space for protecting the vibratingportion and a conductive opening; a step of forming a first wiring so asto be connected to the element wiring through the conductive opening; astep of forming a second insulating layer including a second conductiveopening on the insulating layer; a step of forming a second wiring so asto be connected to the first wiring through the second conductiveopening; and a step of forming the external terminal so as to beconnected to the first wiring through the second wiring.
 17. A methodfor manufacturing a piezoelectric component comprising a piezoelectricelement including at least one vibrating portion and an element wiringconnected to the vibrating portion, which are formed on a substrate; andan external terminal, the method comprising: a step of manufacturing thepiezoelectric element by forming said at least one vibrating portion andthe element wiring connected to the vibrating portion on the substrate;a step of forming a protective layer for protecting the vibratingportion in the piezoelectric element; a step of forming an insulatinglayer including an opening serving as space for protecting the vibratingportion and a conductive opening; a step of forming a first wiring so asto be connected to the element wiring through the conductive opening; astep of forming a second insulating layer including a second conductiveopening on the insulating layer; a step of forming a second wiring so asto be connected to the first wiring through the second conductiveopening; and a step of forming the external terminal so as to beconnected to the first wiring through the second wiring.
 18. A methodfor manufacturing a piezoelectric component according to claim 11,further comprising a step of polishing the substrate.